1. Field of the Invention
The invention provides an antenna, and more specifically, a multi-frequency antenna.
2. Description of the Prior Art
In the prior art, an inverted F antenna is usually used to realize a radio signal switch. As those skilled in the art know, the basic inverted F antenna includes a radiating element. One end of the radiating element connects with a ground element, and the middle of the radiating element is used as the feeding point of the signal. The ground element and the signal feeding point form two transverse portions of an F shape (The radiating element becomes the back of the F shape.). The length of the antenna has a relationship with a radiating frequency of transmitting and receiving. However, the simple inverted F antenna only supports a single-frequency for transmitting and receiving radio signals. It cannot integrate multiple frequencies for transmitting and receiving radio signals. The length of the radiating element is relatively long, so compact size requirements of the information industry cannot be met. In addition, U.S. Pat. No. 6,861,986 provides a kind of multiple-frequency application for an inverted F antenna. However, the antenna uses two ends in a straight line radiating element to radiate two frequencies. Thus, the size of the radiating element is not compact.